The increasing prevalence of capture and storage for images and video by digital means has introduced the problem of verifiable authenticity. Photographic fraud is a matter of growing concern and numerous attempts have been made to solve the issue using digital watermarking of images [1-5].
A majority of watermark research has been devoted to obtaining a solid understanding of the information theory involved and to software implementation. A recent trend has been the increasing development of hardware-based solutions for digital watermarking. While the software approach holds an advantage in terms of flexibility, certain computational restrictions may arise when attempting to operate at video rates or in a portable device. In 2000, DeStrycker et al. used a TriMedia VLIW DSP to implement real-time embedding and detection of video watermarks for broadcast monitoring [6]. In 2001, Tirkel and Hall of Monash University in Australia proposed a SIMM card for digital camera with an on-board EPLD to embed an invisible watermark [7]. Mathai et al., of the University of Toronto, have done a significant amount of work converting the JAWS watermarking algorithm into VLSI form for real-time video stream embedding [8,9]. As part of a secure JPE Gencoder, Mohanty et al. have outlined a 0.35 μm CMOS chip for watermarking of images [10]. In 2004, they produced another chip for visible watermarking, integrated in a Digital Still Camera architecture [11]. Garimella et al. also recently reported a 0.13 μm CMOS VLSI chip for watermarking of 8-bit grayscale images based on difference encoding [12].
There is still a need in the art for a CMOS chip with integral watermarking which may be conveniently detected and which may allow for unique identification of the sensor itself.